A 68-year-old man with hypertension and diabetes mellitus presents to the emergency department with palpitations and dyspnea for 6 hours. His wife reports he has been increasingly fatigued over the past 2 weeks. On examination, pulse is irregularly irregular at 128/min, blood pressure 145/92 mmHg, and there are bilateral crackles at the lung bases. ECG shows absent P waves, irregular RR intervals, and a ventricular rate of 120–140 bpm. Chest X-ray shows pulmonary edema. Troponin I is normal. What is the most appropriate immediate management?

Explanation

## Clinical Presentation Analysis This patient has **new-onset atrial fibrillation with rapid ventricular response (RVR) complicated by signs of heart failure (pulmonary edema)**. The critical question is whether the patient is **hemodynamically stable or unstable**. ### Key Clinical Features - Irregularly irregular pulse at 128/min (RVR) - Bilateral crackles and dyspnea → pulmonary congestion/edema - **Blood pressure 145/92 mmHg** → NOT hypotensive; hemodynamically STABLE - Normal troponin (excludes acute coronary syndrome) - Duration < 12 hours (recent onset) ## Hemodynamic Stability Assessment **Hemodynamic instability** requiring immediate cardioversion is defined as: - **Hypotension** (SBP < 90 mmHg) - Altered mental status - Ongoing ischemic chest pain - Cardiogenic shock This patient has a **BP of 145/92 mmHg** — he is **hemodynamically stable** despite pulmonary congestion. Pulmonary edema alone, in the absence of hypotension or shock, does NOT mandate emergency cardioversion per AHA/ACC guidelines. ## Management Algorithm for AF with RVR **High-Yield:** In hemodynamically **stable** AF with RVR and heart failure/pulmonary edema, the immediate priority is **rate control** to reduce the ventricular rate, which in turn reduces myocardial oxygen demand and allows time for cardiac output to improve. **Key Point:** **Intravenous diltiazem (20 mg IV bolus)** is the preferred agent for acute rate control in hemodynamically stable AF with RVR. It acts within minutes, effectively slowing AV nodal conduction and reducing ventricular rate. (AHA/ACC AF Guidelines; Harrison's Principles of Internal Medicine, 21e, Ch. 226) ### Why NOT the other options? - **Option B — Immediate synchronized DC cardioversion:** Reserved for hemodynamically **unstable** AF (hypotension, shock, altered consciousness). This patient's BP is 145/92 mmHg — cardioversion is NOT indicated as the immediate step. Cardioversion may be considered electively after rate control and stabilization. - **Option A — Oral digoxin:** Oral route is inappropriate in an emergency setting. Digoxin has a slow onset (hours), is a weak rate-control agent, and is not first-line for acute AF with RVR. Even IV digoxin is considered inferior to diltiazem or beta-blockers for acute rate control. - **Option C — IV amiodarone 300 mg bolus:** This dose/regimen is used for **ventricular arrhythmias** (e.g., VF/pulseless VT in ACLS). For AF, amiodarone is a rhythm-control agent with slow onset; it is not the preferred immediate rate-control drug in stable AF with pulmonary edema. ## Why Intravenous Diltiazem? 1. **Rapid onset** (2–7 minutes) → quickly reduces ventricular rate 2. **Effective AV nodal blockade** → slows conduction, reduces RVR 3. **Hemodynamically stable patient** → no contraindication to diltiazem 4. **Reduces myocardial oxygen demand** → indirectly improves pulmonary congestion 5. **Standard of care** per AHA/ACC guidelines for stable AF with RVR **Clinical Pearl:** Use caution with diltiazem in patients with **severely reduced EF (HFrEF)** due to negative inotropy. In such cases, IV amiodarone or digoxin may be preferred for rate control. However, in this vignette, no prior EF data is provided and the patient is hemodynamically stable, making diltiazem the best immediate choice. [cite: Harrison 21e Ch 226; AHA/ACC/HRS 2023 AF Guidelines]